Catalytic apparatus



Feb. 28, 1928.

A. O. JAEGER CATALYTIC APPARATUS Filed Jan.19, 1927 11 Sheets-Sheet 1 ENTOR ATTORNEYS Feb. 28, 1928. 1,660,511

A. 0. JAEGER CATALYTIC APPARATUS Filed Jan. 19. 1927 ll Sheets-Sheet 2 ATTORNEYS Feb. 28, 1928. 1,660,511

A. o. JAEGER CATALYTIC APPARATUS Filed Jan.19, 1927 11 Sheets-Sheet. 3

INVENTOH PHO/VS 0 15656 ATTO R N FAYS Feb. 28, 1928.

A. O. JAEGER CATALYTIC APPARATUS Filed Jan.19, 1927 11 Sheets-Sheet 4 INVENTOR ALPHO/VS 0 \ZIEGER JW ATTORNEYJ Feb. 28, 1928.

A. O. JAEGER CATALYTIC APPARATUS Filed Jan.l9, 1927 11 sheets-Sheet 5 INVENTOR A: Pfl /VS 0- JZEGER ATTORNEY;

Feb. 28, 1928.

A. o. JAEGER CATALYT I C APPARATUS Filed Jan.l9, 1927 11 Sheets-Sheet 5 INVENTOR A1 P/ra/vs 0- 7215652 wil W ATTORN EYS Feb. 28, 1928. 1,660,511

A. o. JAEGER CATALYTIC APPARATUS Filed Jan.l9, 1927 11 SheetS-Shaat 7 /Zf ATTORNEY;

Feb. 28, 1928.

A. O. JAEGER CATALYTIC APPARATU Filed Jan.19. 1927 11 Sheets-Sheet 8 R R5 w 2 M W. n 0 A w Feb. 28, 1928.

A. O. JAEGER CATALYTIC APPARATUS Filed Jan.19, 1927 11 Sheets-Sheet 9 2 m5 Mm T6 N 2 Wm wfnom 5 4 mm Feb. 28, 1928. 1,660,511

A. o. .JAEGER CATALYTIC APPARATUS Filed Jan.19, 1927 11 Sheets-Sheet l0 jay/5 unl- ERRXWEEKM Qua-s ack Q2 J INVENTOR K 14! P/m/vs a Jr M r W ATTORNEYS Feb. 28, 1928.

A. O. JAEGER CATALYTIC APPARATUS Filed Jzin.19, 1927 11 sheets-sheet 11 IN VENT OR 5 2 H i N A 0 S m m flv. B

emu Fob. 28, ms.

UNITED STATES PATENT OFFICE.

ALPHONB O. J'AIGEB, O1 OBAI'I'ON, PINNSYLVAN IA, ASSIGNOB T was 8m (DH- PANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OI DELAWARE CATALYTIC APPARATUS.

Application Med January 19, 1991. mm m. 182,000.

This invention relates to methods and apparatus for carrying out catalytic reactions in the vapor phase.

Vapor phase catalytic reactions, and, par

ticularly such reactions as are strongly exothermic, present numerous difliculties in controlling the heat of reaction, The gases striking the first layers of contact mass cpntain the greatest concentration of reacting l0 ingredients, and, therefore, produce the most intense reaction. The reaction speed slowly decreases as it nears completion, necessitating considerable length of travel through the catalyst.

Overheating may have a number of serious results. In the first place, the catalyst ma he destroyed if it is not resistant to lug; temperatures. Secondly, the reaction may carried too far as, for example, in certain organic oxidations where it is desired to pro duce'an intermediate oxidation product. A third difficulty arises in reactions in which too high a temperature results in an incomplete reaction, as in many exothermic reactions, overheatin tends to push the equilibrium away fi'om complete reaction. The relative importance of these disadvantages varies, of course, with the particular reaction to be carried out and the principles of the invention, which will be described 'be low, mustbe adapted to any particular reaction with due consideration to the conditions under which it takes place.

It. has been proposed in the past tocarry out exothermic catalytic reactions in the presence of powerful cooling agents, either liquids or gases, or to subdivide the catalyst so that heat is given off by radiation. When properly applied, these methods prevent overheating and may prevent in some reactions, the production of undesired byproduct. There is, however, a very serious disadvantage in that the whole of the catalyst is cooled and the reaction speed is lowered, particularly in the portions of the catalyst which encounter the almost completely reacted gases. This brings about a serious dilemma. Either the catalyst layer must be made enormously long with a tremendous cost in catalyst, or else the speed, with which the reaction gases pass through the catalyst, must he reduced to a very low point, which also results in an uneconomical utilization of the catalyst. A further difliculty arises due to the fact that the cooling, which may be satisfactory and essential to the ortions of the catalyst encountering the free gases, may be too great for those portions which encounter gases that are partly reacted.

According to the resent invention, large outputs and an exce lent temperature regulation are made possible by dividing the reaction into a lurality of converters, the first converter being provided with powerful cooling means and in the preferred embodiments of the invention with self regulating cooling means. The second, or following, converters may be provided with no cooling means at all or with less intense cooling means and the catalyst depth and converter arrangement can be accurately controlled so asto provide for the very best catalytic conditions at any polnt in t e reaction.

It is also possible in some of the preferred embodiments of the present invention to enormously increase the output by running the powerfully cooled first converter with gas speeds far in excess of any economical speed in a single converter. The powerful cooling means prevents overheating and the fact that excessive gas speeds do not give a satisfactory high percent of yield for commercial work is immaterial, since the partly reacted gases are then passed through other converters wherein the catalyst is arranged so as to bring about a maximum percentage conversion. The total output may be in some cases from two to five times that which is possible in a single converter having the same amount of catalyst.

The division of the process into a number of converters also permits accurately controlling the gas temperature on entering any of the converters by suitable heat exchangers, either fixed or adjustable, situated between the different converters. This is a very important advantage of the present invention in the case of reactions such as the catalytic oxidation of sulfur dioxide where it is essential to keep the temperature under control not only in the catalyst layers, which are subjected to fresh gases, but also in the last catalyst layers which are required to effect the last few percent of reaction. This is due to the fact that the reaction is an equilibrium reaction which is relatively sensitive to temperature. The arrangement of heat exchangers between the converters is also important in many organic oxidations such as for example oxidatlons of aromatic compounds where intermediate components of low heat stability are formed and where it is necessary to rapidly cool down the part-- ly reacted gases before subjecting them to contact with additional catalyst layers. Important as the possibility of temperature adjustment between converters is, however, the invention is not limited to this feature and in some cases where it is not so essential to provide for an interconverter temperature ad'ustment this feature may be omitted and suc processes and arrangements are included in the present invention.

The invention will be described in greater detail in connection with the drawings, in which Figure 1 illustrates the combination of a converter with automatic gas cooling with an ordinary layer converter of the Grillo type, heat exchangers being provided between the converters;

Fig. 2 illustrates a. modified construction of automatically gas cooled converter and layer converter with an adjustable intercooler;

Fig. 3 illustrates a modified form of automatically gas cooled converter with an individual heat exchanger combined with an ordinary layer converter;

Fig. 4 illustrates a combined automatic gas cooled converter and layer converter associated with a separate layer converter and heat exchanger;

Fig. 5 illustrates the combination of a Tentelew converter combined with a layer converter without intercooler;

Fig. 6 illustrates a modified Tentelew converter combined with a single layer converter without intercooler;

Fig. 7 shows a modified automatic gas cooled converter associated with a double layer converter without intercooler;

Fig. 8 is a horizontal section through Fig. 7 along the line 8-8;

Figure 9 illustrates a combination of another type of Knietsch tubular converter with a layer converter;

Fig. 10 illustrates a combined annular and layer converter associated with two different types of separate layer converters in series;

Fig. 11 i1 ustrates the combination of two automatic gas cooled converters in series with a separate layer converter;

Fig. 12 illustrates a liquid cooled tubular converter in series with a separate layer converter; and

Figs. 13 and 14 illustrate the combination of two automatically gas cooled converters in series, one of them being provided with evaporative means for equalizing the cool- Ih the construction shown in Fig. 1, the

gas cooled converter I consists in a shell 1, top piece 2, bottom piece 3, perforated catalyst support 4 and u per artition 5. A catalyst 6 is supporte on t e plate 4 and extends almost up to the plate 5. In the catalyst are embedded closed bottom tubes 7 having open ends extending above the catalyst evel. Open end tubes 8 hang from the plate 5 and extend practicall to the bottom of the tubes 7. Suitable ori cc plates 9 are mounted in the upper ends of the pcripheral tubes 8, the orifices decreasing in size from the central tubes toward those on the eriphery. Battles 10 are also arranged in t e inlet chamber formed between the plate 5 and the top piece 2. The catalyst is filled into the converter through holes in the plate 5 which are then closed with plugs 11. An emergency cold gas main 12 connects with the upper portion of the catalyst space by the short connecting pipes 13 and a suittable drainage pi e 14 is provided for removin spent cata yst.

Wit the converter is associated a second converter II of a simple two-layer Grillo type. This converter consists in a shell 15, top piece 16, bottom piece 17, erforated catalyst trays 18 and catalyst ayers 19. Bailles 20 are placed in the inlet chamber between the bottom piece 17 and the lower tray 18 in order to distribute and mix the incoming gases.

Two heat exchangers III and IV are associated with the converters and consist respectively in shells 30 and 40, upper pieces 31 and 41, lower pieces 32 and 42, heat exchange tubes 33 and 43, and baffles 34 and 44.

A pipe 21 connects the bottom chamber of the converter I to the bottom chamber of the converter II and is provided with a valve 22. A branch 23 provided with a valve 24 enters the pipe 21 between the converter I and the valve 22 and connects the pipe to the bottom piece 32 of the heat exchanger III. Pipe 25 connects the top piece 16 of the converter II to the top piece 41 of the heat exchanger IV, while a pipe 26 providcd with a valve 27 connects the upper portion of the shell 40 of the heat exchanger IV to the top piece 2 of the converter I. A branch pipe 28 runs from the upper portion of the shell of the heat exchanger III to the pipe 26, entering the latter at a point between the valve 27 and the converter I. A pipe 29 connects the pipe 26 with the lower portion of the shell 30 of the heat exchanger III and a pipe connects the top piece 31 of the same heat exchanger with the pipe 21. The pipe 29 which is provided with the valve 36 enters the pipe 26 between the valve 27 and the heat exchanger IV, whereas the pipe 35 enters the pipe 21 between the valve 22 and the converter II. The heat exchanger IV is further provided with an inlet into the lower portion 0 f no the shell and an outlet 46 from the bottom piece 42.

In operation, gases pass in the direction indicated by the arrows into the shell of the heat exchanger IV through the inlet pipe and flowing over the tubes 43 in a sinuous path dclincd by the perforated baflles 44, pass through the pipe 26 into the top p:ece 2 of the converter The gases may pass directl into the converter or they may go throng 1 the pipe 29 into the heat exchanger III flowing over the tubes 33 in a sinuous )atli defined by the perforated bafil'es 34 and inally flow into the pipe 26 throu h the pipe 28. The relative proportion of the gases flowing directly into the converter and those flowing by way of the heat exchanger is determined by suitable adjustment of the valves 27 and 36. B this means, the gases can be given the desired degree of heat before entering the converter.

After entering the converter, the gases are thoroughly mixed and distributed by the bafile plates 10 and pass down through the central tubes 8 in amounts which increase from the periphery toward the center, since the orifice plates 9 provide smaller passages near the periphery gradually increasing toward the center to the full size of the tubes. After passing down throu h the tubes 8, the gases strike the bottom 0 the tubes 7, their flow is reversed and they flow upwardly through these tubes in direct heat exchanging relation with the catalyst, finally issuing from the top of the tubes where their direction is again chan ed and they flow downwardly through the catalyst, passing out throu h the perforated plate 4 into the bottom c number of the converter. Additional hot or cold gases can be directly passed into the catalyst from the main 12 through the pipes 13.

The converter pos -csses tremendous cooling powers due to the construction of the heat exchanging elements which are not claimed in the present invention. but form the subject-limiter of the application of Jaeger & Bertsch. Serial No. 100.818. lilcd April 9. 1926. The provision of means for circulating a rclat ivcly larger amount of gas through the central tubesv is also not claimed in this invention. but forms the subjectmattcr of my copending application, Serial No. 144,496, filed October 27. 1926.

As the central portions of the catalyst are not as ell'ectivcly cooled as the peripheral portions due to the. lack of radiation from the shell, additional gas flow serves to compensate for this effect and brings about an even temperature throughout the whole of the catalyst layer, preventing undesirable overheating in the center. As the cooling effect of the heat exchanging elements va ries substantially directly as the amount of gas passed through the converter and the amount of heat evolved is also substantially proportional to the amount of gas flowing throu h, the converter will be satisfactorily coole( throughout awide range of gas velocities andflautomatically adjusts itself to fluctuations, acting thus as an automatic as cooled converter. Since the radiation mm the shell, however, does not increase with the increased flow of gas, it may be desirable to compensate for the lack of increase in coolingetl'ect by passing direct 1y some cold gas through the main 12. Sinularly, the temperature can also be varied by varying the temperature of the incoming gases, i. e., by varying the proportion of the Incoming gases which pass through the heat. exchanges III.

The automatic cooling features of the converter make it possible to operate it under enormous overloads, sometimes amounting to more than 5 times the normal converter rating without producing undesirable overheating. Of course, with greatly increased gas velocities, the percentage of conversion will naturally drop, but as the artly rcacted gases are later on to be subjected to further conversion, this factor isnaturally of no importance and the converter can be pushed to the limit, permitting enormous ou tlputs per unit of catalyst.

he hot gases from converter I are led to converter II where they pass through the catalyst layers and the reaction is completed. The temperature of the gases as they leave converter I, especially when the latter is pushed to outputs many times higher than those normally obtained, are at a temperature which is usually too high to permit cooling the reaction to a satisfactory de-- gree of completion even though they may not be hot enough to damage the catalyst in converter II. For this reason, the temperature of the gases passing out into the pipe 21 is advantageously decreased by passing part or all of the gases through the heat exchanger III. This is effected by suitable adjustment of the valves 22 and 24 which determine the relative proportions of gas flowing through the heat exchanger Ill. The flow. of course, is directlwthrough the tubes 33 into the top piece 31 and thence through the pipe 35 back into the pipe 21. lVhen a portion only of the gases are passed through the heat exchanger III. the temperature of the united gas streams into the )ottom piece 17 of the converter II may not be uniformly mixed and for this pur-- pose, bailies 20 are provided in the couverter II to etl'ect a thorough mixing and hence, equalization of temperature of the incoming gases. The heat abstracted in the heat exchanger serve of course, to heat up the cold gases which are on their way to converter I.

Passing through the converter II, the

gases are, of course, further heated up, although, usually to a smaller degree than in converter I, since only a small percenta of the reaction takes place in converter The latter converter is provided with little or no cooling, depending solely on the radiation of the converter shell assisted by the fact that the bafile plates drive the gases from the center of the converter into contact with the shell. Strong cooling means are usually not necessary in the second converter as the reaction does not generate suilicient heat to become dangerous. The rcacted gases which are, of course, at approximately reaction temperature or higher, pass from the top piece 16 through the pipe 25 into the top piece 41 of the heat exchanger IV, flowing through the tubes 43 into the bottom piece 42 and thence out through the exhaust opening -16. During their passage through the heat exchanger, the. reacted gases give up a considerable proportion of their heat to warm up the incoming cold gases.

It should be noted that the arrangement of the two converters which are not in heat exchanging contact with each other resents a number of advantages. In the rst place, converter I, which can be forced to enormous outputs, is relatively small compared to its output and as it constitutes the more expensive converter type, a marked saving is thereby effected. Converter II, which can be of the layer type and requires but little cooling provision, is of the cheapest possible construction and can be of a size which is ample to produce a satisfactory percentage yield. In other words, the output of the more expensive portion of the installation is enormously increased which results in a considerable saving.

A further very notable advantage consists in the fact that the two converters are entirely independent in their arrangement and the gas velocity through the catalyst in the converters, which, of course, is determined by the catalyst cross sectional area, can be varied to bring about the best results. Thus, for example, in most reactions tremendous output, but a relatively lower percentage yield, can be efi'ected by using enormous gas velocities and accordingly converter I is usually built with a relatively small catalyst cross section. On the other hand, it is desirable, in order to bring about the highest ercentage yields, to slow up the gas speed-t rough the last catalyst layers in order to give the reaction, which is practically always an equilibrium reaction, time to proceed as completely as possible in the desired direction. This is easily efiected by providing a very large cross section in the converter II with a correspondingly sluggish gas flow and resulting i h ercenta e yield. This feature is not emp asized in t e drawin which are purely dia rammatic. It shou be understood that t e relative cross section of gas passage in converters I and II are to be determined by the particular condition of the reaction which is to be carried out therein.

A further important feature for many reactions lies in the fact that the catalyst layer in converter II is not exposed to radiant heat from the catalyst in converter I. As a result, there is no tendency for any portion of the catalyst in converter II to become overheated and its temperature is determined purely by the condition of the gas passing throng it This is clearly brought out by a comparison of the present invention with the modification shown in Fig. 9 and particularl in Fi 11 of the application of Jaeger g Bertsc Serial No. 100,818, filed April 9, 1926, referred to above. In these figures, the layer of uncooled catalyst is (placed below the cooled catalyst layer in or er tocomplete the reaction. The layer, however, is exposed to the full radiant heat of the highly eated catalyst layer above it and the gases also convey a large amount of heat to it by convection. The layer, therefore, is heated to a bi h temperature which in many cases markedIy decreases the yield. The present invention which permits a control of the temperature of the catalyst layer in each converter dependent only on the gas conditions permits operatin under the most favorable conditions at al times and in many reactions, particularly reactions which are relatively sensitive to temperature, a very great increase in efliciency is possible.

It should be understood that the drawin s are purely diagrammatic in nature, on y such structural features being shown as are necessary to an understandin of the invention. In every case, the exigencies of the particular reactions to be carried out will determine What structural desi n is to be used and all necessary structural eatures and accessories and the like will be used as will be apparent to the skilled chemical engineer. Suitable provision for charging the converter with catalyst will also be provided as is indicated in some of the drawings. These details of structure and accessories do not per se form an part of the present invention, which, on t e contrary, is applicable to any desired converter structure.

Fig. 2 illustrates a somewhat modified arrangement of two converters similar to that shown in Fig. 1. Analogous parts are given the same reference characters. The installation consists in converters I and II, the intercooler III and a heat exchanger IV. The design of the heat exchanger IV is identical with that shown in Fig. 1 and converter II is also similarly arran ed.

Converter I consists in a modified type of I perforated converter such as that shown in Fig. 12 of the application of J aeger & 'Bertsch, referred to above. In this converter, the to piece 2 is not directly connected to the she 1, but is separated therefrom by two flanged shell segments 38, carryin an additional artition 39 which is rovided with tubes 4 extending through a ditional holes in the partition 5 and belng provided with deflecting plates 48 and perforations 49 at their lower ends. The details of the design are the same as shown in Figs. 12 and of the ap lication ofJaeger Bertsch above referre to.

The top piece 2 is connected to a gas main 50 which is provided with a valve 51 the upper portion of the shell 40 of the heat exchan or IV connects to the chamber formed b the flange 38 ,and partitions 5 and 39 t rough the pipe/26, into which pi an additional gas main 52 is led wine is provided with a valve 53. Instead of tubes havi one open end and one closed end embedde in the catalyst, tubes 57 are provided having a closed lower end and an upper end welded or fastened onto the inner tubes 8. The tubes 57 are embedded in the catalyst for their whole length and are provided with crforations 56 at their upper end. The mner tubes 8 are preferably provided with perforations at their lower ends.

Hot gases from the bottom of the converter I pass through a i e 21 either directly into the converter or throu h an intercooler III. This intercooler II consists in a U-shaped pipe 54, both legs leading into the pipe 21, in which the valve 22 is placed between the two legs. A valve 58 is provided in the left or entering le of the U-shaped tube and a valve 59 1s a so provided in the upper bend of the U-shaped tube. A cross ipe 60 rovided with a valve 61 joins the rig 1t leg 0 the U tube to the left leg between the valves 58 and 59. The tube is not )rovided with heat installation and may, i desired, be provided with suitable heat dissipating means such as fins or the like. Part or all of the hot gases in pi e 21 me be caused to ass throughout t e whole ength of the U tuhe or across the cross pipe 60 of the U tube as desired. In the former case, the valve 61 is closed and valve 59 is opened, and in the latter case, valve 59 is closed and valve 61 is opened. The relative amount of gas passing through the U tube and direct through the pipe 21 is, of course, determined by suitable a justment of the valves 22 and 58.

In operation, gas passes in through the pipe 45 and thence throu h the heat exchanger IV into the cham er between the partitions 5 and 39 in a manner similar to that described in connection with Fig. 1. Thence, the gas passes down through the innor tubes 8, up along the inner wall of the tubes 57 out through the perforations 56 and down through the catalyst layer. Additional cold gas may be introduced through the main 50 into the top iece 2, whence it p through the tubes 4? and directly through the catalyst. The deflecting plates 48 prevent blasts of cold gas strlklng restricted portions of the catalyst and cooling them to a point where the reaction will no longer proceed. In passing through the i as 47, of course, the gas is partly warme y the heated gas entering through the pi 26. The general effect is similar to that in ig.'1, but or some urposes is preferable, as the additional col gas, instead of entering directly into the catalyst space, as shown in Fig. 1, is first partly warmed by the heated gases and is less apt to produce abrupt or ocalized tem erature changes.

Where ad itional cooling is desired, cold gas can be introduced throu h the main 52 into the pipe 26. In genera the modification shown in Fig. 2 is preferable where highly exothermic reactions are encountered. It is not as suitable for reactions which reuire a high inlet gas temperature. It s iould be understood, of course that there is no particular necessity of combining an intercooler with the particular design of converter I. On the contrary, an mtercooler may be used in place of a. heat exchanger III in the arrangement shown in Fig. 1 and vice versa a heat exchanger can be used in Fig. 2 instead of an intercooler. In general, in the drawings, I have attempted to illustrate several different types of converter, without, however, limiting the invention to the particular combination of converters shown.

Fig. 3 illustrates a combination of a converter I, a second converter II, and a heat exchanger IV, without an external heat exchanger or intercooler between the converters. This function is performed by an extension of the tubes 7 and 8 which pass through the catalyst layer and which in their bottom reaches perform the function of heat exchangers, coolin off the heated gases and at the same time eating up the incoming gases, bafiles 62 being provided to increase the path of gastravel. The arrangement of converter II and heat exchanger IV is identical with that shown in Fig. 1 and the gas flow during 0 eration is similar, being clearly shown by t e arrows.

The internal heat exchanger combined with the converter I and which is similar in desi to that shown in Fig. 6 of the J aeger & ertsch application, referred to above presents many advantages from a structural standpoint. The arrangement is exceedingly compact and permits the maintenance of a relatively even temperature throughout the catal st zone, since the gases assing upwardly through the tubes 7 are rst heated up not only during their passage through the tubes 8, but b the hot reaction gases flowing over their ower reaches so that at no point do relatively cold gases come in heat exchanging contact with the catalyst. is This uniform moderate cooling, which, however, possesses all the automatic advantages of increase in heat evolution is especi 1} suitable for reactions which require hig inlet gas temperatures and which are not excessively exothermic.

No provision is made in the converter for varying the relative flow of gas through the central and eripheral heat exchan ing elements, but this can be efiected, as s own in Figs. 1 and 2, wherever it may prove desirab e.

Fig. 4 illustrates a somewhat different arrangement of converters without intercoolers. The converter I is an'inverted convertar, similar in design to that illustrated in Fig. 14 of the J aeger & Bertsch application, above referred to, but being .provided with an additional catalyst layer 63 arranged somewhat similar to that shown in Fig. 11 of the same application. The baflie 64 is placed between the main catalyst layer and the layer 63 in order to prevent gases from the main catalyst layer directly striking the layer 63 and to provide a more thorou h mixture of the partly reacted gases. T e baflle also serves the purpose of directin the ases against the converter shell an there y enhancing the cooling. In converter 11, it should be noticed that the catalyst layers increase in depth in the direction of gas flow which is desirable in many cases, as the pro essively reacted ses require an increasing y lon contact with the catalyst in order to resu t in substantially complete conversion. A similar variation of catalyst depth may, of course, be utilized in the second converters shown in the other fi ures. The heat exchanger IV and converter I are inverted, but 0 erate in precisely the same manner as in t e other figures.

The arrangement in Fig. 4 presents certain advantages where the exothermic reaction carried out tends to proceed with extreme rapidity in the portion of the contact mass which encounters the fresh gases, but which tends to slow u in the passage through further layers 0 catalyst and may be insuflicient to maintain sufiicient heat for completion. The inverted converter structure shown in Fig. 4 and the absence of an intercooler between the converters permits maintaining-the catalyst layer 63 and the catalyst mass in the second converter at suitable tem eratures. It is also possible to use catalyst ayers of great depth in the second converter which is advantageous for complete conversion. It is also frequently desirable to provide a second converter with much more active catalysts to make up for as the decreasing concentration of unreacted gases. In such cases, it may evenbe desirable to provide a certain amount of cooling of the uses between converter I and converter l This may be eflected by omitting heat insulation from the pi e 21 or by providing a suitable intercoo er or heat exchanger. In general, it should be understood that wherever the connecting pipe or pipes between the converters are permitted to radiate considerable amounts of heat,tl1ey are really acting as intercoolers and it is impossible to draw any sharp line between a mere connecting pipe and a definitely designed intercooler. n fact, every uninsulated connecting pipe should be considered as an intercooler and is intended to be included under this term whenever it is used in the specification and claims.

F i 5 illustrates a very simple combination etween the well known Tentelew converter and-a simple layer converter of the Grillo type. The Tentelew converter I consists in an outer shell 64, upper piece 65, bottom piece 66, partition 67, catalyst tubes 68 and bafile plates 69. Gas enters through the mains and 52, the latter being provided with a valve 53, and the main 50 being connected to the top piece 65. The ases, which are thoroughly mixed and deflected by the bafllc 69, surround the catalyst tubes and finally pass down through the catalyst in the tubes. Owing to the enormous radiation surface of the tubes, a satisfactory cooling is efl'ected which is semi-automatic in nature in that the cooling increases to a certain extent with increased gas flow but not strictly proportionately thereto as in the as cooled converter shown in the foregoing gures. It is accordingly ossible with reactions which are not un uly sensitive to push the Tentelew converter to outputs very much in excess of its normal output with, of course, a corresponding decrease in percentage lyield.

T e partly reacted gases then pass through the pipe 21 into the converter II, as in the other figures. An intercooler or heat exchanger me be used if desired or the pi e 21 may be eft uninsulated to erform t e functions of an intercooler. 0 course, the gases passing out from the converter II may pass t rough an external heat exchanger in order to heat up the incoming gases entering the main 50 as is shown in the other figures. In general, it should be understood that the intercoolers or heat exchangers between the converters may be omitted in any of the constructions shown Without affectin the broad scope of the invention, but for best results in strongly exothermic reactions, some form of intercooler or heat cxchan er is exceedingly desirable and in some delicate reactions essential, and, therefore, constitutes an important specific feature of the present invention, although not limiting its broad scope. 1:0

fore, forced to pass down over the tubes in through the perforations 71 and up between the tubes 70 and the tubes 68 before passing down through the catalyst in the atter. By this means, the semi-automatic Tentelew converter in which the cooling is by radiation is transformed into a fully automatic, gas cooled converter of tremendous efiectiveness, the cooling varying directly as the gas speed and permitting enormously increased outputs. The arrangement of the two converters aside from the additional tubes 70 is identical with that in Fig. 5 and the same considerations and ad vantages described with respect thereto apply to the converters shown in Fig. 6, which embodiment in addition possesses the advantage of a fully automatic gas cooled converter I.

Figs. 7 and 8 illustrate a combination of a novel type of gas cooled converter with an ordinary layer converter. The gas cooled converter consists in a shell 72, top piece 73, bottom piece 74, and perforated partition 75. On the artition is laced a closed end tube 76 wit the close end down. Surrounding this tube are a series of concentric, cylindrical troughs 77 and 78. Between the tube 77 and the troughs 78 the catalyst is arranged in concentric annuli 79 (see Fig.

8). Between the outer catalyst ring 79 and the converter shell 72 is placed an annular hollow metal ring 80in order to prevent undue cooling of the outer catalyst ring by radiation.

A closed end hollow metal ring 81 is laced over the closed end tube 76 and ring 7 so that the open end of the inner wall extends down to the bottom of thetube 76 being provided with the perforations 82 and the outer wall extends down to the bottom of the ring 77, being provided at its lower end with the perforations 83. A second concentric ring 84 similarly has its inner wall extending into the ring 77 and is provided at its lower end with the erforations 85 and its outer wall extendin own into the outer ring 78, being provide at its lower end with the perforations 86. A third concentric annular member 87 of L-shaped cross section is arranged with the outer end of its horizontal face connected to the shell 72 and the vertical leg extending into the ring 78 and provided at its lower end with the per forations 88. It will be apparent that the inner wall of the inner annulusBl forms a tube open at both ends and extending into the tube 76 and that the outer wall of this annulus with the inner wall of the annulus 84 defines an annular space extending down into the annulus 77. A similar space is also formed by the vertical leg of t e ring 87 and the outer wall of the annulus 84 and extends into the annulus 78. The s entering through the main 50 mixes, i desired,

with other s entering through the main 52 provide with the valve 53, and passes down throu h the central space of the annulus 81 and the spaces between the annuli 81, 84 and 87 to the bottom of the tube 76 and the annuli 77 and 78, where the direction of gas flow is reversed and the gases pass a wardly in contact with the walls of the tu s 76 and annuli 77 and 78 in heat exchanging relation with the catalyst rings. After issuing from the to of these spaces, they then again reverse an pass downwardly through the catalyst. It will be noticed that the effect is almost identical with that of the converters shown in Figs. 1 to 4 except that instead of small tubularielcments embedded in the catalyst, annular cooling elements are so embedded. The cooling, of"

course, is in direct pro ortion to the amount of gas passing throug and undue cooling of the outer catalyst ring is prevented by the air space between it and the converter shell. The operation of the converter is the same as that shown in-Fig. 1, for example, but the annular construction of elements presents many advantages from a structural standpoint. t is easily possible to vary the thickness of the catalyst rings so as to get an absolutely even cooling which is much more diflicult with embedded elements as the distance between elements is not entirely uniform, whereas in the catalyst rings, shown in Fig. 7, the distance between the ring walls is constant.

'lhe converter II is similar in design to that shown in the foregoing iigurcs and the operation is the same. If desired, an intercooler or heat exchanger can be interposed between the converters or the pipe 21 can be left uninsulated so as to perform the functions of an intercooler as described in connection with the foregoing figures.

Fig, 9 illustrates a combination of a well known type of converter of the Knietsch type, extensively used for catalytic sulfuric acid, with an ordinary layer converter. In the converter I, the catalyst is arranged in tubes 91, which are mounted in partitions 92 and 93 and form with the tubes. top piece 94, an internal unit. This unit is surrounded by an intermediate shell 95 and an outer shell 96. Gases from the main 50 pass directly into the space between the shells 95 and 96, entering at the upper portion of the shell and passing downwardly into perforated distributing tubes 98, whence the gases pass up between and around the catalyst tubes 91 and finally through the space between an external top iece 99 and to the top piece 9-1 into the utter, being thorou hly mixed by passing around baffles 100. T he gases thus form a gas Jacket which prevents heat losses b radiation from the shell 95. A portion 0 the gases pass through the pipe 97 provided with the valve 101 directly into the lower distributing tube 98. The gases after passing downwardly through the tubes into the bottom chamber below the partition 93 are conducted to converter 11 through the pi e 21.

Converter I is not ful y automatically gas cooled, since the cooling does not increase proportionately with the gas flow, but an excellent cooling is achieved and the converter can be pushed to outputs many times the normal output without overheating particularly in reactions such as the catalytic oxidation of sulfur dioxide. The percentage yield. of course, drops, but is brought up to a high point by the converter II. Suitable heat exchangers and intercoolers, as shown in some of the other figures, may, of course, be used.

Fig. 10 shows a combination of an annular gas cooled converter with two layer converters in series. The annular converter. which is similar to that described and claimed in my co-pending application, Serial No. 146,525, filed Nov. 5, 1926, and which does not per se form any part of the present invention, consists in a converter shell 102, top piece 103, bottom piece 104, and upper partltion 105. From this upper partition depends a perforated annular catalyst chamber having an inner wall 106, outer wall 107, and annular catalyst layer 108. The bottom of this chamber is fastened to a lower partition 109 which does not extend fully across the converter. A central open-ended tube 110 also depends from the partition 105, surrounded by a concentric cylindrical wall 111 extending ahnost down to the partition 109 and being provided with perforations throughout its lower reaches. Baflle cylindcrs 112 and 113 extend upwardly from the partition 109 between the tube 110 and baflie 111 and between the baflle 111 and catalyst chamber respectively. The upper reaches of the open-ended cylinder 113 are provided with perforations.

An uncooled catalyst layer 114 is supported by the perforated plate 115 in the lower portion of the converter and bafile plates 116 are arranged between it and the partition 109. A pipe 21 connects the chamber divided by the bottom piece 104 and the plate 115 with the la er converter II provided with three cata yst layers, whence the gases after further reaction pass through the pipe 117 into the deep single layer converter II" containing a catalyst layer 118 suppprted by a perforated plate 119, bafiles 120 in provided for diffusing th gas over the cata yst.

. In 0 eration, the fresh gases coming in throng 1 main 50 with or without additional gas from the main 52, regulated b the valve 52' pass downwardly throug the tube 110 and then through a sinuous path over the battle tubes and cylinders 111, 112 and 113, finally passing outwardly throu h the catalyst and then downwardly over t e baflles 116, through the catalyst layer 114 and thence in series through the converters 11 and II". The converter I is not automatically gas cooled, but the catalyst annulus 108 is so thin that the heat is rapidly radiated to the baille cylinders and to the shell of the converter and the gases flowing through the catalyst la 'er rapidly carry the heat to the converter 5 iell. The bafiles are kept cool by the incoming gases which are in turn heated up thereby. The faster the gases pass through the apparatus, the shorter the period of time they are exposed to the heat of the radiant heat from the catalyst and to the hot bafile cylinders and correspondingly, the cooler they are when they encounter the catalyst. There is thus an increase in cooling effect with increased gas speed which is enhanced by the fact that the faster the gases pass through the catalyst, the greater is the tendency for them to carry the heat generated in the catalyst to the converter shell 102 a ainst which they impinge before being de ected downwardly. Additional coolin v is, of course, effected by the baflles 116 w iich force the gases to flow outwardly into contact with the lower portion of the shell where they are still further cooled before passing through the catalyst layer 114. Some of the battles 116 may also be connected to the shell 102 and serve to conduct heat to it, although their primary function is to deflect and thoroughly mix the partly reacted gases. The thin catalyst layers in converter I produce a relatively low percentage yield so that the gases striking the converter II still contain a relativel considerable amount of unreacted gases. he catalyst layers in converter II are thin and the period of time during which the gases are encountered with the catalyst at any one time is short which tends to prevent overheating in converter II". The gases assing out from this converter are reactor to a large extent and are then passed through a very deep catalyst layer in converter II where the reaction is carried to completion.

The arrangement of a series of layer converters after. a gas cooled converter can, of course, also be used in connection with gas cooled converters shown in the other figures and in many cases presents important advantages.

the highl efiective modified Tentelew type illustrated in Fig. 6: while the converter 1" is similar to the type shown in Fig. 4, and is provided with a very deep catalyst layer.

he pipe 121 connects the two converters I and while the pipe 21 connects converters I and II which is an ordinary three layer converter having catal st layers of increasing thickness in the irection of flow. This arrangement of catalysts permits enormous gas velocities in reactions which are very strongly exothermic. The amount of catalyst in proportion to the cooling surface in the converter I is very small an despite violent reaction, there is no danger of overheatin In converter I", the catalyst layer is muc thicker and the gas cooling is much less eflicient, since, of course. the gases themselves are hot. The final reaction takes place in the converter II where the layers become progressively deeper and dee r, permitting the last few percent of yie d to be achieved.

The arrangement of the two s cooled converter types shown, both of which are antomatic, is un'unusually effective one. Not only are the converters automatically cooled in proportion to the amount of gases flowing theret rough, but the system, as a whole, is to a considerable extent self balancing. Thus, for example, the increase of speed of v s flow in converter 1 increases the cooling in that converter and decreases the percentage yield and, therefore, the exit temperature of the gases which then enter the converter I at a lower temperature, at higher speed, and therefore, compensate for the in creased heatin effect in this latter converter due to t is larger proportion of the reaction taking place therein. The automatic proportioning of cooling between the two converters is thereby efiected and it is possible to enormously increase the yield per unit time and per unit of apparatus by greatly increasing t e gas s eed w ich would not be practicable if a sin e converter were used because it would resu t in too low a percentage yield. In the arrangement shown in Fig. 11, however, this decreased percentage yield is compensated by the increased amount of reaction taking place in the other two converters so that the system as a whole permits very high yields per hour without a reduction in the yield rcenta e and with a most satisfactory regu ation o cooling.

Of course, other combinations of gas cooled converters can be used and Fig. 11 is intended only to illustrate two typical gas cooled converters, as thus, for example, one converter may be automatic and the other semi-automatic and the like. In eneral, it is desirable to place the most eflicient,

to verter is connected fully automatic converter as the first in the series, since the amount of heat evolved therein tends to be a maximum per pound' of catalyst. The exact eat and pro'portioning with cooling efliciency will, of course, be determined in any particular case by the skilled mechanical en meer.

In Fi 12 a liquid coole converter I is combin with an ordinary layer type converter II. The liquid cooled converter is of conventional desi consisting in a shell 132, perforated partitions 122 and 123 connected by catalyst tubes 124. A bottom piece 125 and top piece 126 completes the converter structure. The space surroundin the tubes 124 between the artition 122 an 123 is filled with a suitab 0 high boiling liquid which may be mercury or other low meltmg alloys or may be an suitable liquid under pressure. he liqui chamber is connected at its up r part with a radiator by the pipe 127. e radiator consists in a lower header 128, upper header 129 and radiating tubes 130, a suitable safety valve 131 being provided to prevent the excess pressures. The piece 126 of the conto the layer converter II by a pipe 21 and the bottom piece 125 is connecte to an inlet gas main.

In olperation, the reaction gases pass in throu the inlet main into the bottom piece 125, t ence up through the catalyst tubes 124 into the top iece 126 and out through the pipe 21 into t e converter II. The heat evolved in the tubes 124 is transmitted to the surrounding liquid which boils, the vapors ascending into the tubes 130 which are exposed to air or may, if desired, be water cooled. The vdpors condense and the liquid flows back throng] the pipe 127. In this manner, by a suitable adjustment of the valve 131, the temperature can be maintained substantially constant and owin to the great heat absorbing capacity of t e liquid, very high as speeds are possible.

A suitab e intercooler or heat exchanger ma be inserted between the converter 1 an 11 as has been described in connection with some of the foregoing fi res. If a heat exchanger is used, it may connected to the inlet gas so as to warm up the latter where it is proved desirable. A second heat exchanger after the converter II may also be provided as is described in connection with Fig. 1 and some of the other figures.

The liquid cooled converter shown in Fig. 12 is purely diagrammatic and any other suitable type of liquid cooled converter may be used.

In Fi 13, a combination of two difierent types 0 automatically gas cooled converters is shown associated with heat exchan ers. The first converter provides for a two-p ase liqluid vapor temperature equalizin system, w ereas the second converter is o t e or- 

